Involvement of the p66Shc protein in glucose transport regulation in skeletal muscle myoblasts.
The p66(Shc) protein isoform regulates MAP kinase activity and the actin cytoskeleton turnover, which are both required for normal glucose transport responses. To investigate the role of p66(Shc) in glucose transport regulation in skeletal muscle cells, L6 myoblasts with antisense-mediated reduction (L6/p66(Shc)as) or adenovirus-mediated overexpression (L6/p66(Shc)adv) of the p66(Shc) protein were examined. L6/(Shc)as myoblasts showed constitutive activation of ERK-1/2 and disruption of the actin network, associated with an 11-fold increase in basal glucose transport. GLUT1 and GLUT3 transporter proteins were sevenfold and fourfold more abundant, respectively, and were localized throughout the cytoplasm. Conversely, in L6 myoblasts overexpressing p66(Shc), basal glucose uptake rates were reduced by 30% in parallel with a approximately 50% reduction in total GLUT1 and GLUT3 transporter levels. Inhibition of the increased ERK-1/2 activity with PD98059 in L6/(Shc)as cells had a minimal effect on increased GLUT1 and GLUT3 protein levels, but restored the actin cytoskeleton, and reduced the abnormally high basal glucose uptake by 70%. In conclusion, p66(Shc) appears to regulate the glucose transport system in skeletal muscle myoblasts by controlling, via MAP kinase, the integrity of the actin cytoskeleton and by modulating cellular expression of GLUT1 and GLUT3 transporter proteins via ERK-independent pathways.
Natalicchio
Annalisa
A
Dept. of Emergency and Organ Transplantation, Section on Internal Medicine, Endocrinology and Metabolic Diseases, Univ. of Bari, Piazza Giulio Cesare, 11, I-70124 Bari, Italy.
De Stefano
Francesca
F
Perrini
Sebastio
S
Laviola
Luigi
L
Cignarelli
Angelo
A
Caccioppoli
Cristina
C
Quagliara
Anna
A
Melchiorre
Mariangela
M
Leonardini
Anna
A
Conserva
Antonella
A
Giorgino
Francesco
F
D008841:Actin Cytoskeleton / Q000378:metabolism / Q000502:physiology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D055785:Gene Knockdown Techniques; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1 / Q000378:metabolism / Q000502:physiology; D051274:Glucose Transporter Type 3 / Q000378:metabolism / Q000502:physiology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D032448:Myoblasts, Skeletal / Q000187:drug effects / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D055765:Shc Signaling Adaptor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1
D051272:Glucose Transporter Type 1; D051274:Glucose Transporter Type 3; D034741:RNA, Small Interfering; D055765:Shc Signaling Adaptor Proteins; C528035:Shc1 protein, rat; C495679:Slc2a1 protein, rat; C495690:Slc2a3 protein, rat; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D005947:Glucose